Two cars moving in opposite directions approach each other with speed of $22\, m s^{-1}$ and $16.5 \, m s^{-1}$ respectively. The driver of the first car blows a horn having a frequency $400 \,Hz.$ The frequency heard by the driver of the second car is ..... $Hz$ (velocity of sound is $340 \, m s^{-1}$)
NEET 2017, Medium
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The required frequency of sound heard by the driver of second car is given as
$\mathrm{v}^{\prime}=\mathrm{v}\left(\frac{v+v_{o}}{v-v_{s}}\right)$
where $v=$ velocity of sound
$v_{o}=$ velocity of observer, $i . e .,$ second car
$v_{s}=$ velocity of source $i . e .,$ first car
$v^{\prime}=400\left(\frac{340+16.5}{340-22}\right)=400\left(\frac{356.5}{318}\right)$
$v^{\prime} \approx 448 \mathrm{Hz}$
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